The Democratic administration in Bucks County yesterday criticized Coroner Thomas J. Rosko for not adhering to the county's plan to reduce personnel costs by 15 percent.

What raised the anger of Democratic Commissioners Carl F. Fonash and Lucille M. Trench was the decision by the Republican-controlled Salary Board to grant Rosko's secretary a raise that, when added to a 3 percent raise awarded earlier this year, will amount to 13 percent.

Most courthouse employees are receiving 3 percent raises.

According to the action by the Salary Board, the job title of Rosko's secretary was changed from "administrative assistant" to "executive secretary." The title change carries a raise in pay from $18,600 a year to $20,400 a year.

The secretary is Antoinette M. Daly, a Republican committeewoman from Doylestown.

Trench pointed out that Daly already has received the 3 percent raise that all other county employees were awarded for 1986.

Therefore, Trench said, the raise granted to Daly by the Salary Board, coupled with the earlier pay increase, means the Republican leader will receive a 13 percent raise.

Trench said Rosko, a Republican, is a "row officer totally oblivious to what we're trying to achieve. He has bypassed the commissioners to get a raise for this employee."

Fonash said the county has for some time been working toward reducing the courthouse payroll by 15 percent by the end of the year. Fonash said he doubts Rosko will be able to meet that goal since Daly is his only staff employee.

The commissioner said a review board has been set up to screen applications by department heads who want to give raises of more than 3 percent to employees.

The review board, which is composed of Personnel Director Albert Simone, Finance Director Richard C. Gore and County Administrator William H. Rieser, only screens requests that can be acted on by the commissioners.

Since he is an independently elected row officer, Rosko does not have to submit his applications to the review board. Nevertheless, Fonash said, the coroner should have gone through the board to adhere to the county's policy to reduce the payroll.

"It's out of sync with what we're trying to do around here," said the commissioner.

Rosko went to the Salary Board to get the job description changed. Members of the board, when acting on matters involving the coroner's office, include the coroner, the controller and the three commissioners.

Members of the Salary Board who signed off on the job change were Rosko, Controller Daniel Lawler and Commissioner Andrew L. Warren. All three are Republicans.

Rosko could not be reached for comment.

Warren defended the action. The commissioner said he understands Daly will be taking on extra duties under her new job title.